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Diffusion tensor imaging of normal white matter maturation from late childhood to young adulthood: Voxel-wise evaluation of mean diffusivity, fractional anisotropy, radial and axial diffusivities, and correlation with reading development

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NEUROimage 2008年第2期41卷 223-232页

作者： Qiu, Deqiang Tan, Li-Hai Zhou, Ke Khong, Pek-Lan Univ Hong Kong Dept Diagnost Radiol State Key Lab Brain & Cognit Sci Hong Kong Hong Kong Peoples R China Univ Hong Kong Dept Linguist State Key Lab Brain & Cognit Sci Hong Kong Hong Kong Peoples R China Chinese Acad Sci Inst Biophys Beijing 100080 Peoples R China

Using diffusion tensor MR imaging (DTI) and advanced voxel-wise analysis tools, we study diffusivity and anisotropy changes of white matter from late childhood to young adulthood, and correlate quantitative diffusion indices with Chinese and English reading performance scores. Seventy-five normal healthy school going ethnic Chinese students and young adults of three age groups were recruited (group 1, n = 24, mean +/- SD = 7.4 +/- 0.3 years;group 2, n = 27, mean +/- SD = 10.3 +/- 0.5 years;group 3, n = 24, mean +/- SD = 22.8 +/- 2.3 years). DTI was performed with 3 mm isotropic resolution to cover the entire brain. Voxel-wise analysis was performed using Tract-Based Spatial Statistics (TBSS) to localize regions of white matter showing significant changes of fractional anisotropy (FA), mean diffusivity (MD), and axial and radial diffusivities between groups. We found increased FA and decreased MD with increasing age in regions of cerebellar white matter, right temporal white matter, and a large portion of the superior frontal and parietal white matter driven by both the reduction of radial diffusivity and axial diffusivity with the former to a greater extent. Changes were continual from late childhood to young adulthood. Findings were confirmed by region-of-interest analysis in specific white matter tracts. After controlling for the effect of age, significant correlation was found between diffusion indices of the anterior limb of the left internal capsule and Chinese reading score (p = 0.05), and of the corona radiata and English reading score (p = 0.026 and p = 0.029 for left and right, respectively). These DTI indices likely reflect the multiple biological processes that occur during brain development which provide the neural substrate for ongoing functional connectivity including for reading development. (c) 2008 Elsevier Inc. All rights reserved.

关键词： Adolescent Adult Anisotropy Brain/growth & development Brain/physiology Child Diffusion Magnetic Resonance Imaging Female Humans image processing, computer-assisted Male Reading

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A distinct [¹⁸F]MPPF PET profile in amnestic mild cognitive impairment compared to mild Alzheimer's disease

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NEUROimage 2008年第3期40卷 1251-1256页

作者： Truchot, L. Costes, N. Zimmer, L. Laurent, B. Le Bars, D. Thomas-Anterion, C. Mercier, B. Hermier, M. Vighetto, A. Krolak-Salmon, P. Univ Lyon 1 F-69677 Bron France Hop Neurol F-69677 Bron France CERMEP Imagerie Vivant F-69003 Lyon France Inst Fed Neurosci Lyon F-69394 Lyon 03 France Memory Res Resource Ctr Alzheimers Dis Lyon Lyon France Hop Bellevue Serv Neurol F-42100 St Etienne France Memory Res Resource Ctr Alzheimers Dis St Etienne St Etienne France

To date, two positron emission tomography ( PET) studies have explored 5-HT1A receptor density in the hippocampus of Alzheimer's disease (AD) patients. They showed early changes of 5-HT1A receptors in this brain region, known to have a dense serotonergic innervation. These studies only reported measurements in hippocampus. In the present PET study, we used an antagonist of 5-HT1A receptors, the [F-18] MPPF (1) to explore 5-HT1A receptor density in the whole brain of AD patients at a mild stage of dementia and amnestic mild cognitive impairment (aMCI) patients compared to a control population;(2) to explore more precisely the 5-HT1A receptor density in the limbic brain regions of AD patients and aMCI patients compared to controls. Voxel-based analyses were performed to assess differences in the [F-18] MPPF binding potential ( BP) between AD patients and aMCI patients compared to controls. Analyses of whole-brain [F-18] MPPF BP showed a global decrease in AD brains in contrast with a global increase in aMCI brains. In AD brains, a significant decrease of BP was detected in hippocampus and parahippocampal gyrus, whereas a significant increase of BP was observed in the inferior occipital gyrus in aMCI brains. These whole brain results are in accordance to hippocampal data reported in a previous study, showing an increase of [F-18] MPPF binding in the aMCI group contrasting with a decrease in the AD group. Altogether, these results suggest the implication of a compensatory mechanism illustrated by an up regulation of serotonergic metabolism at the aMCI stage before a breakdown of this mechanism at the AD stage. This difference of serotonergic receptor labeling allows to distinguish the groups of aMCI patients from mild AD patients with specific [F-18] MPPF PET profiles for each patient group. (C) 2008 Published by Elsevier Inc.

关键词： Aged Alzheimer Disease/psychology Alzheimer Disease/radionuclide imaging Amnesia/psychology Amnesia/radionuclide imaging Brain/radionuclide imaging Cognition Disorders/psychology Cognition Disorders/radionuclide imaging Female Functional Laterality/physiology Humans image processing, computer-assisted Limbic System/radionuclide imaging Male Middle Aged Piperazines/diagnostic use Positron-Emission Tomography Pyridines/diagnostic use Radiopharmaceuticals/diagnostic use Radiopharmaceuticals/diagnostic use Receptor, Serotonin, 5-HT1A/metabolism

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Piecemeal recruitment of left-lateralized brain areas during reading: A spatio-functional account

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NEUROimage 2008年第3期43卷 581-591页

作者： Levy, Jonathan Pernet, Cyril Treserras, Sebastien Boulanouar, Kader Berry, Isabelle Aubry, Florent Demonet, Jean-Francois Celsis, Pierre Radboud Univ Nijmegen Donders Inst Brain Cognit & Behav NL-6525 ED Nijmegen Netherlands INSERM U825 F-31000 Toulouse France Univ Toulouse 3 Inst Sci Cerveau Toulouse IFR 96 F-31000 Toulouse France Western Gen Hosp Dept Clin Neurosci SFC Brain Imaging Res Ctr Edinburgh EH4 2XU Midlothian Scotland CHU Toulouse Univ Hosp Dept Neuroradiol F-31000 Toulouse France

Neuroimaging studies of reading converge to suggest that linguistically elementary stimuli are confined to the activation of bilateral posterior regions, whereas linguistically complex stimuli additionally recruit left hemispheric anterior regions, raising the hypotheses of a gradual bilateral-to-left and a posterior-to-anterior recruitment of reading related areas. Here, we tested these two hypotheses by contrasting a repertoire of eight categories of stimuli ranging from simple orthographic-like characters to words and pseudowords in a single experiment, and by measuring BOLD signal changes and connectivity while 16 fluent readers passively viewed the stimuli. Our results confirm the existence of a bilateral-to-left and posterior-to-anterior recruitment of reading related areas, straightforwardly resulting from the increase in stimuli's linguistic processing load, which reflects reading processes: visual analysis, orthographic encoding and phonological decoding. Connectivity analyses strengthened the validity of these observations and additionally revealed an enhancement of the left parieto-frontal information trafficking for higher linguistic processing. Our findings clearly establish the notion of a gradual spatio-functional recruitment of reading areas and demonstrate, to the best of our knowledge, the first evidence of a robust and staged link between the level of linguistic processing, the spatial distribution of brain activity and its information trafficking. (C) 2008 Elsevier Inc. All rights reserved.

关键词： Adult Brain/physiology Brain Mapping Brain Mapping Female Functional Laterality/physiology Humans image processing, computer-assisted Magnetic Resonance Imaging Male Pattern Recognition, Visual/physiology Reading

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Themolecular basis for gray and white matter contrast in phase imaging

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NEUROimage 2008年第4期40卷 1561-1566页

作者： Zhong, Kai Leupold, Jochen von Elverfeldt, Dominik Speck, Oliver Univ Magdeburg Dept Biomed Magnet Resonance Fac Nat Sci D-39120 Magdeburg Germany Univ Hosp Freiburg Dept Diagnost Radiol D-79106 Freiburg Germany

Direct magnetic resonance phase images acquired at high field have been shown to yield superior gray and white matter contrast up to 10-fold higher compared to conventional magnitude images. However, the underlying contrast mechanism is not yet understood. This study demonstrates that the water resonance frequency is directly shifted by water-macromolecule exchange processes (0.040 ppm/mM for bovine serum albumin) and might be a major source of contribution to in vivo phase image contrast. Therefore, magnetic resonance phase imaging based on the proposed contrast mechanism could potentially be applied for in vivo studies of pathologies on a macromolecular level. (c) 2008 Elsevier Inc. All rights reserved.

关键词： Body Water/chemistry Brain/anatomy & histology Brain/physiology Brain Chemistry/physiology Electromagnetic Fields Electromagnetic Fields Hemoglobins/metabolism Humans image processing, computer-assisted Magnetic Resonance Imaging Serum Albumin, Bovine/chemistry

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Socioeconomic status predicts hemispheric specialisation of the left inferior frontal gyrus in young children

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NEUROimage 2008年第3期40卷 1392-1401页

作者： Raizada, Rajeev D. S. Richards, Todd L. Meltzoff, Andrew Kuhl, Patricia K. Univ Washington Inst Learning & Brain Sci Seattle WA 98195 USA Univ Washington Sch Med Dept Radiol Seattle WA 98195 USA

Reading is a complex skill that is not mastered by all children. At the age of 5, on the cusp of prereading development, many factors combine to influence a child's future reading success, including neural and behavioural factors such as phonological awareness and the auditory processing of phonetic input, and environmental factors, such as socioeconomic status (SES). We investigated the interactions between these factors in 5-year-old children by administering a battery of standardised cognitive and linguistic tests, measuring SES with a standardised scale, and using fMRI to record neural activity during a behavioral task, rhyming, that is predictive of reading skills. Correlation tests were performed, and then corrected for multiple comparisons using the false discovery rate (FDR) procedure. It emerged that only one relationship linking neural with behavioural or environmental factors survived as significant after FDR correction: a correlation between SES and the degree of hemispheric specialisation in the left inferior frontal gyrus (IFG), a region which includes Broca's area. This neural-environmental link remained significant even after controlling for the children's scores on the standardised language and cognition tests. In order to investigate possible environmental influences on the left IFG further, grey and white matter volumes were calculated. Marginally significant correlations with SES were found, indicating that environmental effects may manifest themselves in the brain anatomically as well as functionally. Collectively, these findings suggest that the weaker language skills of low-SES children are related to reduced underlying neural specialisation, and that these neural problems go beyond what is revealed by behavioural tests alone. (c) 2008 Elsevier Inc. All rights reserved.

关键词： Auditory Perception/physiology Child, Preschool Frontal Lobe/physiology Functional Laterality/physiology Humans image processing, computer-assisted Magnetic Resonance Imaging Neuropsychological Tests Psychomotor Performance/physiology Reading Social Class Speech Perception/physiology

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Functional re-recruitment of dysfunctional brain areas predicts language recovery in chronic aphasia

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NEUROimage 2008年第4期39卷 2038-2046页

作者： Meinzer, Marcus Flaisch, Tobias Breitenstein, Catorina Wienbruch, Christian Elbert, Thomas Rockstroh, Brigitte Univ Konstanz Dept Psychol D-78457 Constance Germany Univ Konstanz Dept Clin Psychol & Neuropsychol D-78457 Constance Germany Univ Konstanz Dept Gen Psychol D-78457 Constance Germany Univ Munster Dept Neurol D-48129 Munster Germany

Functional recovery in response to a brain lesion, such as a stroke, can even occur years after the incident and may be accelerated by effective rehabilitation strategies. In eleven chronic aphasia patients, we administered a short-term intensive language training to improve language functions and to induce cortical reorganization under rigorously controlled conditions. Overt naming performance was assessed during functional magnetic resonance imaging (fMRI) prior to and immediately after the language training. Regions of interest (ROIs) for statistical analyses were constituted by areas with individually determined abnormally high densities of slow wave generators (identified by magnetoencephalography prior to the language intervention) that clustered mainly in left perilesional areas. Three additional individually defined regions served to control for the specificity of the results for the selected respective target region: the homologue area of the individual patient's lesion, the mirror image of the delta ROI in the right hemisphere and left hemispheric regions that did not produce a significant amount of slow wave activity. Treatment-induced changes of fMRI brain activation were highly correlated with improved naming of the trained pictures, but selectively within the pre-training dysfunctional perilesional brain areas. Our results suggest that remodeling of cortical functions is possible even years after a stroke. The behavioral gain seems to be mediated by brain regions that had been partially deprived from input after the initial stroke. We therefore provide first time direct evidence for the importance of treatment-induced functional reintegration of perilesional areas in a heterogeneous sample of chronic aphasia patients. (C) 2007 Published by Elsevier tnc.

关键词： Adult Aged Aphasia/etiology Aphasia/physiopathology Aphasia/rehabilitation Brain/physiopathology Brain Ischemia/complications Brain Ischemia/physiopathology Chronic Disease Data Interpretation, Statistical Echo-Planar Imaging Female Humans image processing, computer-assisted Language Magnetic Resonance Imaging Magnetoencephalography Magnetoencephalography Male Middle Aged Neuropsychological Tests Psychomotor Performance/physiology Recovery of Function/physiology Recruitment, Neurophysiological/physiology Stroke/complications Stroke/physiopathology Visual Perception/physiology

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Spatio-temporal dynamics of replication and transcription sites in the mammalian cell nucleus

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CHROMOSOMA 2008年第6期117卷 553-567页

作者： Malyavantham, Kishore S. Bhattacharya, Sambit Alonso, William D. Acharya, Raj Berezney, Ronald Dept Biol Sci Univ Buffalo NY 14260 USA SUNY Buffalo Dept Biol Sci Buffalo NY 14260 USA Fayetteville State Univ Dept Math & Comp Sci Fayetteville NC 28301 USA Penn State Univ Dept Comp Sci & Engn University Pk PA 16802 USA

To study when and where active genes replicated in early S phase are transcribed, a series of pulse-chase experiments are performed to label replicating chromatin domains (RS) in early S phase and subsequently transcription sites (TS) after chase periods of 0 to 24 h. Surprisingly, transcription activity throughout these chase periods did not show significant colocalization with early RS chromatin domains. Application of novel image segmentation and proximity algorithms, however, revealed close proximity of TS with the labeled chromatin domains independent of chase time. In addition, RNA polymerase II was highly proximal and showed significant colocalization with both TS and the chromatin domains. Based on these findings, we propose that chromatin activated for transcription dynamically unfolds or "loops out" of early RS chromatin domains where it can interact with RNA polymerase II and other components of the transcriptional machinery. Our results further suggest that the early RS chromatin domains are transcribing genes throughout the cell cycle and that multiple chromatin domains are organized around the same transcription factory.

关键词： Cell Nucleus/metabolism Chromatin/metabolism Chromosome Positioning DNA Replication Hela Cells Humans image processing, computer-assisted RNA Polymerase II/metabolism S Phase Time Factors Transcription, Genetic

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Defining functional areas in individual human brains using resting functional connectivity MRI

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NEUROimage 2008年第1期41卷 45-57页

作者： Cohen, Alexander L. Fair, Damien A. Dosenbach, Nico U. F. Miezin, Francis M. Dierker, Donna Van Essen, David C. Schlaggar, Bradley L. Petersen, Steven E. Washington Univ Sch Med Dept Neurol St Louis MO 63110 USA Washington Univ Sch Med Dept Radiol St Louis MO 63110 USA Washington Univ Sch Med Dept Anat & Neurobiol St Louis MO 63110 USA Washington Univ Sch Med Dept Pediat St Louis MO 63110 USA Washington Univ Sch Med Dept Psychol St Louis MO 63110 USA

The cerebral cortex is anatomically organized at many physical scales starting at the level of single neurons and extending up to functional systems. Current functional magnetic resonance imaging (fMRI) studies often focus at the level of areas, networks, and systems. Except in restricted domains, (e. g., topographically-organized sensory regions), it is difficult to determine area boundaries in the human brain using fMRI. The ability to delineate functional areas non-invasively would enhance the quality of many experimental analyses allowing more accurate across-subject comparisons of independently identified functional areas. Correlations in spontaneous BOLD activity, often referred to as resting state functional connectivity (rs-fcMRI), are especially promising as a way to accurately localize differences in patterns of activity across large expanses of cortex. In the current report, we applied a novel set of image analysis tools to explore the utility of rs-fcMRI for defining wide-ranging functional area boundaries. We find that rs-fcMRI patterns show sharp transitions in correlation patterns and that these putative areal boundaries can be reliably detected in individual subjects as well as in group data. Additionally, combining surface-based analysis techniques with image processing algorithms allows automated mapping of putative areal boundaries across large expanses of cortex without the need for prior information about a region's function or topography. Our approach reliably produces maps of bounded regions appropriate in size and number for putative functional areas. These findings will hopefully stimulate further methodological refinements and validations. (c) 2008 Elsevier Inc. All rights reserved.

关键词： Algorithms Brain/physiology Brain Mapping Brain Mapping Cerebral Cortex/physiology Data Interpretation, Statistical Humans image processing, computer-assisted Magnetic Resonance Imaging Neural Pathways/physiology Oxygen/blood Reproducibility of Results

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Impaired semantic processing during sentence reading in children with dyslexia: Combined fMRI and ERP evidence

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NEUROimage 2008年第1期41卷 153-168页

作者： Schulz, Enrico Maurer, Urs van der Mark, Sanne Bucher, Kerstin Brem, Silvia Martin, Ernst Brandeis, Daniel Univ Zurich Dept Child & Adolescent Psychiat CH-8032 Zurich Switzerland Cornell Univ Weill Med Coll Sackler Inst Dev Psychobiol Ithaca NY 14853 USA Univ Zurich Univ Childrens Hosp MR Ctr CH-8032 Zurich Switzerland Univ Jyvaskyla Agora Ctr Jyvaskyla Finland Univ Zurich Ctr Integrat Human Physiol CH-8032 Zurich Switzerland

Developmental dyslexia is a specific disorder of reading acquisition characterized by a phonological core deficit. Sentence reading is also impaired in dyslexic readers, but whether semantic processing deficits contribute is unclear. Combining spatially and temporally sensitive neuroimaging techniques to focus on semantic processing can provide a more comprehensive characterization of sentence reading in dyslexia. We recorded brain activity from 52 children (16 with dyslexia, 31 controls) with functional magnetic resonance imaging (fMRI) and event-related potentials (ERP) in two separate counterbalanced sessions. The children silently read and occasionally judged simple sentences with semantically congruous or incongruous endings. fMRI and ERP activation during sentence reading and semantic processing was analyzed across all children and also by comparing children with dyslexia to controls. For sentence reading, we analyzed the response to all words in a sentence;for semantic processing, we contrasted responses to incongruous and congruous endings. Sentence reading was characterized by activation in a left-lateralized language network. Semantic processing was characterized by activation in left-hemispheric regions of the inferior frontal and superior temporal cortex and by an electrophysiological N400 effect after 240 ms with consistent left anterior source localization. Children with dyslexia showed decreased activation for sentence reading in inferior parietal and frontal regions, and for semantic processing in inferior parietal regions, and during the N400 effect. Together, this suggests that semantic impairment during sentence reading reduces dyslexic children's response in left anterior brain regions underlying the more phasic N400 effect and subsequently modulates the more sustained BOLD response in left inferior parietal regions. (c) 2008 Elsevier Inc. All rights reserved.

关键词： Brain Mapping Brain Mapping Cerebral Cortex/physiology Child Data Interpretation, Statistical Dyslexia/pathology Dyslexia/physiopathology Echo-Planar Imaging Electroencephalography Evoked Potentials/physiology Female Humans image processing, computer-assisted Intelligence Tests Longitudinal Studies Magnetic Resonance Imaging Male Oxygen/blood Psychomotor Performance/physiology Reading Semantics Speech Perception/physiology

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NEUROimage 2008年第1期40卷 342-352页

作者： Hutchison, Emmette R. Blumstein, Sheila E. Myers, Emily B. Brown Univ Dept Cognit & Linguist Sci Providence RI 02912 USA Brown Univ Dept Neurosci Providence RI 02912 USA

The discrimination of voice-onset time, an acoustic-phonetic cue to voicing in stop consonants, was investigated to explore the neural systems underlying the perception of a rapid temporal speech parameter. Pairs of synthetic stimuli taken from a [da] to [ta] continuum varying in voice-onset time (VOT) were presented for discrimination judgments. Participants exhibited categorical perception, discriminating 15-ms and 30-ms between-category comparisons and failing to discriminate 15-ms within-category comparisons. Contrastive analysis with a tone discrimination task demonstrated left superior temporal gyros activation in all three VOT conditions with recruitment of additional regions, particularly the right inferior frontal gyrus and middle frontal gyros for the 15-ms between-category stimuli. Hemispheric differences using anatomically defined regions of interest showed two distinct patterns with anterior regions showing more activation in the right hemisphere relative to the left hemisphere and temporal regions demonstrating greater activation in the left hemisphere relative to the right hemisphere. Activation in the temporal regions appears to reflect initial acoustic-perceptual analysis of VOT. Greater activation in the right hemisphere anterior regions may reflect increased processing demands, suggesting involvement of the right hemisphere when the acoustic distance between the stimuli are reduced and when the discrimination judgment becomes more difficult. (c) 2007 Elsevier Inc. All rights reserved.

关键词： Adult Auditory Perception/physiology Brain/physiology Cerebral Cortex/anatomy & histology Cerebral Cortex/physiology Cues Data Interpretation, Statistical Discrimination (Psychology)/physiology Female Functional Laterality/physiology Humans image processing, computer-assisted Magnetic Resonance Imaging/methods Male Middle Aged Psychomotor Performance/physiology Reaction Time/physiology Regression Analysis Time Perception/physiology Voice

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